Most heat exchangers are designed in such a way that one fluid, usually a gas or liquid, passes through a tube or metal separator, while another fluid circulates around the partition. This allows for the heat exchange to occur without the two fluids mixing together.
A heat exchanger is a mechanical device that functions by transferring heat from one material to another through the process of conduction. The media typically involved in a heat exchange are fluids of varying temperatures.
A common example of a heat exchanger is the radiator of a vehicle. It functions by dissipating the heat coming from the cooling mechanism of the engine by using the cold air outside. The radiator keeps the engine from overheating.